From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
"davej@codemonkey.org.uk" <davej@codemonkey.org.uk>,
"dvyukov@google.com" <dvyukov@google.com>,
Stephane Eranian <eranian@gmail.com>
Subject: Re: perf: fuzzer KASAN unwind_get_return_address
Date: Thu, 17 Nov 2016 09:18:48 -0600 [thread overview]
Message-ID: <20161117151848.7sdss3g4waanxfsk@treble> (raw)
In-Reply-To: <20161117090446.GC3142@twins.programming.kicks-ass.net>
On Thu, Nov 17, 2016 at 10:04:46AM +0100, Peter Zijlstra wrote:
> On Wed, Nov 16, 2016 at 10:48:28PM -0600, Josh Poimboeuf wrote:
> > Peter or Vince, can you try to recreate with this patch? It dumps the
> > raw stack contents during a stack dump. Hopefully that would give a
> > clue about what's going wrong.
>
>
> Here goes... I'll do another run and get you the results of that as
> well.
Thanks, I just waded through this and it turned up some good clues. And
according to 'git blame', you might be able to help :-)
It's not stack corruption. Instead it looks like
__intel_pmu_pebs_event() is creating a bad or stale pt_regs which gets
passed to the unwinder. Specifically, regs->bp points to a seemingly
random address on the NMI stack. Which seems odd, considering the code
itself is running on the same NMI stack.
I don't know much about the PEBS code but it seems like it's passing
some stale data. Either that or there's some NMI nesting going on.
--
Josh
next prev parent reply other threads:[~2016-11-17 17:44 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-15 17:43 perf: fuzzer KASAN unwind_get_return_address Vince Weaver
2016-11-15 18:57 ` Peter Zijlstra
2016-11-15 19:04 ` Dmitry Vyukov
2016-11-15 20:56 ` Josh Poimboeuf
2016-11-15 19:05 ` Vince Weaver
2016-11-15 20:57 ` Josh Poimboeuf
2016-11-16 13:03 ` Peter Zijlstra
2016-11-16 13:18 ` Dmitry Vyukov
2016-11-16 14:37 ` Josh Poimboeuf
2016-11-16 14:49 ` Peter Zijlstra
2016-11-16 14:58 ` Josh Poimboeuf
2016-11-16 14:58 ` Peter Zijlstra
2016-11-17 4:48 ` Josh Poimboeuf
2016-11-17 9:04 ` Peter Zijlstra
2016-11-17 9:13 ` Peter Zijlstra
2016-11-17 9:30 ` Peter Zijlstra
2016-11-17 9:48 ` Dmitry Vyukov
2016-11-17 14:01 ` Josh Poimboeuf
2016-11-17 14:25 ` Vince Weaver
2016-11-17 14:36 ` Josh Poimboeuf
2016-11-17 14:58 ` Dmitry Vyukov
2016-11-17 17:15 ` Vince Weaver
2016-11-17 15:18 ` Josh Poimboeuf [this message]
2016-11-17 16:07 ` Peter Zijlstra
2016-11-17 17:17 ` Peter Zijlstra
2016-11-22 12:30 ` [tip:perf/urgent] perf/x86/intel: Cure bogus unwind from PEBS entries tip-bot for Peter Zijlstra
2016-11-16 15:06 ` perf: fuzzer KASAN unwind_get_return_address Vince Weaver
2016-11-17 15:57 ` [PATCH 1/2] unwind: prevent KASAN false positive warnings in guess unwinder Josh Poimboeuf
2016-11-17 15:57 ` [PATCH 2/2] dumpstack: prevent KASAN false positive warnings Josh Poimboeuf
2016-11-18 9:04 ` [tip:x86/urgent] x86/dumpstack: Prevent " tip-bot for Josh Poimboeuf
2016-11-17 20:26 ` [PATCH 1/2] unwind: prevent KASAN false positive warnings in guess unwinder Josh Poimboeuf
2016-11-18 8:38 ` Ingo Molnar
2016-11-18 9:04 ` [tip:x86/urgent] x86/unwind: Prevent " tip-bot for Josh Poimboeuf
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